It’s no secret that Liv Tyler and Stella McCartney are good girlfriends. Even their mothers were BFFs. “[I’ve known Stella] since she was a baby … yes, seriously,” Tyler’s mom Bebe Buell told PEOPLE Wednesday at the opening of the new Stella McCartney boutique in New York’s Saks Fifth Avenue. “Her mother [Linda] was a very good friend.” However, Tyler and McCartney recall bonding later in life. “I think I met you at Kate [Moss’s] house,” McCartney reminded Tyler during the stylish bash. Regardless of where or how they met, the ladies share secrets, lunches and of course, fashion. “She’s very sweet about sending presents,” Tyler said of her pal. “I should say my favorite things I get to have first are the kids’ line or lingerie. I really appreciate a nice pair of panties.” And her son Milo, 6, appreciates the boys’ clothes — sometimes. “[There are] high-top sneakers that I love … little corduroy trousers and nice sweaters,” Tyler said. “But he would be happy if he could be in his pajamas all day.” Especially when mom tries to dress him up. “I kept trying to put him in the Sergeant Pepper jacket from [McCartney’s collection for] The Gap. He said, ‘Nice try, mummy,'” she laughed. “Liv sends me pictures of Milo all the time in my clothes,” McCartney added. “He’s a beautiful boy, I have to say.” McCartney, herself a mom of four, says her children make great little models, too. “They have very nice clothes at their fingertips,” she shared. “They’re the luckiest kids in town.” —Jeffrey Slonim